# Understanding Impulse and Conservation of Energy in Bouncing Ball Collisions

• xrotaryguy
In summary, the conversation revolves around finding the magnitude and direction of the impulse or net force applied to a 5.00kg ball dropped from 1.20m above the floor. The ball rebounds .700m and the goal is to obtain an answer of 4.28N*s. The individuals discuss finding the velocity before and after hitting the floor using different equations and finally suggest using conservation of energy to solve the problem.
xrotaryguy
I don't know why I'm getting the wrong answer on this one.

A 5.00kg ball is dropped from rest from 1.20m above the floor. The ball rebounds .700m. What are the magnitude, and direction of the impulse or the net force applied to the ball during the collision with the floor?

So I started by finding the velocity of the ball just before and just after hitting the floor.

I use that to find the momentum of the ball before and after hitting the floor.

I find the diference between the two momentums and viola! Wrong answer haha.

The answer is supposed to be 4.28N*s

What am I doing wrong?

Oops, I found velocity with a physics equation that doesn't exist. :-D However, using the V=sqrt(2ax) formula, I still get the wrong answer...

Last edited:
xrotaryguy said:
Oops, I found velocity with a physics equation that doesn't exist. :-D

Yes, you wrote pretty weird things down.

Use, for example, conservation of energy to get the velocities you need.

Yes, you wrote pretty weird things down.

Yeah, and I worked so hard at those images too :P

Ok, I'll try conservation of energy.

Thx

## 1. How does the impulse affect the bounce of a ball?

The impulse, which is the change in momentum of the ball, directly affects the bounce of the ball. When a ball bounces, it experiences a change in momentum due to the impact with the ground. This change in momentum is directly proportional to the impulse and can be calculated using the equation impulse = force x time. Therefore, a larger impulse will result in a higher bounce of the ball.

## 2. What factors affect the impulse of a bouncing ball?

The impulse of a bouncing ball is affected by several factors, including the force of impact, the time of impact, and the elasticity of the ball and surface. A stronger force of impact or longer time of impact will result in a larger impulse, while a more elastic ball and surface will decrease the impulse.

## 3. Can the impulse of a bouncing ball be calculated?

Yes, the impulse of a bouncing ball can be calculated using the equation impulse = force x time. The force can be determined by measuring the mass of the ball and the acceleration due to gravity, while the time of impact can be measured using high-speed cameras or other timing devices.

## 4. How does the height of the bounce relate to the impulse of a ball?

The height of the bounce is directly related to the impulse of a ball. This is because the impulse, which is the change in momentum, is what causes the ball to bounce. A larger impulse will result in a higher bounce, while a smaller impulse will result in a lower bounce.

## 5. How does the surface affect the impulse of a bouncing ball?

The surface that the ball bounces on can greatly affect the impulse of the ball. A harder surface, such as concrete, will result in a larger impulse due to the increased force of impact. A softer surface, such as grass, will decrease the impulse due to the surface absorbing some of the force and reducing the time of impact.

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